Successful organ transplantation is often limited due to ischemic/reperfusion injury. Isolated human hearts deprived of oxygen for more than four hours progressively loose vigor and often do not survive in recipient hosts. Other organs such as the kidney, liver, pancreas and lung are also subject to tissue and cellular damage when removed from their hosts prior to transplantation. This damage is due to hypoxic conditions and a lack of circulation, which normally delivers physiological concentrations of oxygen and nutrients, and removes toxic compounds produced by an organ's cells. Organ transplants have a higher frequency of success when performed immediately after excision from their hosts.
Recent advances have increased the rate of successful organ transplants and organ surgery, such as coronary bypass surgery. The first includes organ preservation and organ perfusion solutions. The second is improved methods and devices for the delivery of organ perfusion solutions to an organ.
Short-term myocardiac preservation is currently provided by cold storage after cardioplegic arrest. A variety of processes exist however differing by the composition of the solution used, the preservation temperature and the administration protocol. Different solutions for arresting and preserving the heart have been developed to protect the myocardium in cardiac surgery. Examples of these solutions include Krebs-Henseleit solution, UW solution, St. Thomas II solution, Collins solution and Stanford solution. (See, for example, U.S. Pat. Nos. 4,798,824 and 4,938,961; Southard and Belzer, Ann. Rev. Med. 46:235-247 (1995); and Donnelly and Djuric, Am. J. Hosp. Pharm. 48:2444-2460 (1991)). Nevertheless, organ rejections still remains due to deterioration in the condition of the transplanted organ between the time of removal and the restoration of blood flow in the recipient.
Restoration of blood flow is the primary objective for treatment of organ tissue experiencing prolonged ischemia, e.g., during transplant. However, reperfusion of blood flow induces endothelium and myocyte injury, resulting in organ dysfunction (Buerke et al., Am J Physiol 266: H128-136, 1994; Lucchesi and Mullane, Ann Rev Pharmacol Toxicol 26: 2011-2024, 1986; and Lucchesi et al., J Mol Cell Cardiol 21: 1241-1251, 1989). The sequential events associated with reperfusion injury are initiated by endothelial dysfunction which is characterized by a reduction of the basal endothelial cell release of nitric oxide (NO) within the first 2.5-5 min post-reperfusion (Tsao and Lefer, Am J Phyiol 259: H1660-1666, 1990). The decrease in endothelial derived NO is associated with adhesion molecule up-regulation on endothelial and polymorphonuclear (PMN) leukocyte cell membranes (Ma et al., Circ Res 72: 403-412, 1993; and Weyrich et al., J Leuko Biol 57: 45-55, 1995). This event promotes PMN/endothelial interaction, which occurs by 10 to 20 min post-reperfusion, and subsequent PMN infiltration into the myocardium is observed by 30 min post reperfusion (Lefer and Hayward, In The Role of Nitric Oxide in Ischemia-Reperfusion: Contemporary Cardiology, Loscalzo et al. (Eds.), Humana Press, Totowa, N.J., pp. 357-380, 2000; Lefer and Lefer, Cardiovasc Res 32: 743-751, 1996; Tsao et al., Circulation 82: 1402-1412, 1990; and Weyrich et al., J Leuko Biol 57: 45-55, 1995).
Chemotactic substances released from reperfused tissue and plasma factors activate PMNs that augment PMN release of cytotoxic substances (i.e. superoxide anion) and contribute to organ dysfunction following ischemia/reperfusion (Lucchesi et al. J Mol Cell Cardiol 21: 1241-1251, 1989; Ma et al., Circ Res 69: 95-106, 1991; Tsao et al., Circulation 82: 1402-1412, 1990; and Tsao et al., Am Heart J 123: 1464-1471, 1992). Superoxide combines with NO to produce peroxynitrite anion thus reducing the bioavailability of NO and promotes endothelial dysfunction and PMN infiltration after myocardial ischemia/reperfusion (Clancey et al., J Clin Invest 90: 1116-1121, 1992; Hansen, Circulation 91: 1872-85, 1995; Lucchesi et al., J Mol Cell Cardiol 21: 1241-1251, 1989; Rubanyi and Vanhoutte, Am J Physiol 250: H815-821, 1986; Tsao et al., Am Heart J 123: 1464-1471, 1992; and Weiss, New Eng J Med 320: 365-375, 1989).
Therefore, there remains a need for a solution of improved quality that can extend the preservation time of an organ for transplantation and protect the organ from reperfusion injury after ischemia, so that the organ can resume proper function after restoration of blood flow.